Pipes and drill collars, among other types of generally tubular conduits, are used in the drilling of oil and gas wells. It may be useful to know the precise measurements of such pipes and drill collars, including the overall profiles and dimensions of conduits extending through the pipes and drill collars. However, it may be difficult to measure dimensions within such conduits, at least in part because they may be long and narrow, making it difficult for measuring equipment to obtain measurements, particularly near the center of the conduit.